Category Tech talk

In addition to the Fundamental Sampling Error, which is the subject of Gy’s theory and its derivations, the Grouping and Segregation Error (GSE) is a function of the size, nature and constitution of the particles, among other factors. The GSE certainly can be reduced through judicious practice, but there are circumstances where the GSE can swamp other errors – you need to be aware of these. This week’s 30 Seconds of Info is from Ian Glacken – Optiro's Director of Geology iglacken@snowdenoptiro.com

30 Seconds of Info - Sampling theory and practice: Should you use Aircore samples in your resource estimate? If carried out to high standards, Aircore samples can approach RC in their level of representivity, although it is not suitable for all commodities and lithologies. It is always worthwhile looking at the relationship between Aircore and other sampling types (RC or DD) within an area where there is more-or-less equal representivity of both sample types; there should be no bias over the range of reasonable ‘ore-grade’ values. This week's 30 Seconds of Info comes from Ian Glacken - Optiro's Director of Geology. iglacken@snowdenoptiro.com

This week's 30 Seconds of Info comes from Paul Blackney - Principal Consultant. Every step of the resource estimation process should be validated in some way: While this may sound onerous and time consuming, it doesn’t need to be. For instance, check the downhole compositing process by determining the total sample length before and after compositing – it should be the same or nearly the same. The cause of any difference should be determined and either corrected or understood before proceeding.

Resource estimation and evaluation. Remember that declustered data statistics are not perfect: Applying declustering is a good idea for many drillhole data sets, but recognise that it’s not a perfect process.  During optimisation of the declustering process, it should be…

This week's 30 Seconds of Info comes from Ian Glacken - Optiro's Director of Geology: Capping before or after compositing? This is a controversial topic which has adherents on both sides, although most believe that capping should be carried out after compositing, when the data has equal support. If you are going to cap before you composite the data, then the capping should be carried out with the variable as ‘metal’ or accumulation (grade times length), rather than just the assay itself. Contact: iglacken@snowdenoptiro.com

If you have conditional bias:  Get more and closer-spaced data, estimate into larger volumes (this generally works – but not always), think about a change of support if this isn’t possible, and choose an estimation method which doesn’t exaggerate the…

Ian Glacken - Director of Geology's 30 Seconds of Advice. Be aware of the limitations of ID estimation: Inverse distance (ID) is often touted as a viable alternative to Ordinary Kriging (OK), and it can be – but you must appreciate its two or three very serious limitations and correct for these. The limitations are that there is no accounting for data clustering (unlike OK) and the choice of a power is essentially arbitrary. As long as you are aware of these issues, ID can sometimes be used as a ‘check’ technique for OK.

This week's 30 Seconds of Info comes from Ian Glacken - Director of Geology: Always look at a range of top-cut (capping) techniques: There is no single ‘magic bullet’ technique for top-cutting a set of data; the top-cut chosen will depend upon the nature of the data, the support of the data and the location of the sample points...

Blanks should never be inserted at regular intervals within the sample stream:  It is always much more easy for automation of the QAQC process that blanks are inserted at regular intervals, but this is not optimal and is in fact…